Router help?

Guys I just sent my macbook back to the wife and got my MBP. She has a two wire router from att on dsl. Her old Toshiba laptop will connect fine but she says on the macbook when she opens safari it says not connected. She says that she clicked on the airport symbol up top and it shows her network checked but it never asked for username and password. Anyone care to take a stab at how to set it up? Thanks

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